1. Field of the Invention
The present invention relates to an ion mobility detecting technique. More particularly, the present invention relates to a sample feeding device for an ion mobility spectrometer and a method for detecting solid and gaseous samples using the sample feeding device. In addition, the present invention also relates to an ion mobility spectrometer having the sample feeding device.
2. Description of the Related Art
Currently commercially available detectors for safety inspection mainly detect harmful substances such as explosives and narcotics by an ion mobility spectrometry. Such detectors comprise a sample feeding device.
The sample feeding device can gasify and desorb solid particles or gas entering into the device. The gasified sample molecules are then introduced into an ionization region by air flow. After that, the ionized sample molecules enter into a drift region. The molecules are identified based on their drift time in the drift region. The actual sample feeding devices are classified as both a gaseous sample feeding device and a solid sample feeding device. A sample collecting paper or a sample collecting rod is provided for the solid sample feeding device. Trace residual substance is collected by wiping a surface of an object under inspection with the collecting paper, and then the collecting paper or the sample collecting rod is inserted into the solid sample feeding device, and thereby information about the residual substance on the surface of the object is obtained through detection. In contrast, the gaseous sample feeding device directly extracts gas released by an object under inspection to detect substance. An early commercially available detector typically has function of feeding only one type of sample, for example SMITH's desktop lonscan—5000DT only having solid sample feeding function. Recently, in order to improve the ability of the sample feeding device, Sample feeding devices with both gaseous and solid sample feeding ability are commercially available. Furthermore, a portion of patents has been applied to the product, for example SABER EXV, SABER 4000, and MMTD of SMTH, whose characteristic is to employ two separate sample feeding inlets. When detecting gaseous sample, it is needed to insert a PTFE sheet at a solid sample feeding inlet to close a sample feeding gas path. The disadvantage of SABER 4000 is that the volume of the sample feeding device is large, and occupies one fifth space of the detector. However, the sample feeding device in the desktop detector generally only has the solid sample feeding ability. These factors make constraint to the miniaturization of the detector and restrict the function of the product.
In viewing of the above, there is a need in the prior art to develop a practical ion mobility spectrometer with solid and gaseous sample feeding apparatus. On one hand, the ion mobility spectrometer has a built-in concentrating device so as to simplify its arrangement and operation procedure; and on the other hand, the detector can sensitively and conveniently detect trace level of the residual solid on the object under inspection and gas with an extremely low concentration.